This invention relates to a wave generator for generating a periodic function wave signal for use with a digital circuit, such as a phase lock loop, a Costas loop and the like.
With the recent advances in digital techniques, a wave generator used in, for example, a phase synchronizing circuit which had previously been fabricated with an analogue circuit may now be fabricated using digitized LSI. With such a digitized phase synchronizing circuit, there is produced a sampled sine wave train y(n), for example, which is phase synchronized with a sampled input train x(n). It is necessary to use a read only memory device (ROM) for generating the value of a sine wave having a phase designated in the circuit. In the case where the number of phase designations in one period of the sine wave is small the output extracted by the phase synchronizing circuit contains a large jitter component which is of course undesirable. On the other hand, when the number of phase designations is increased for the purpose of preventing jitter, it is necessary to increase the capacity of ROM, thus making it difficult to fabricate with an LSI.